Finishes, and why the second container never matches
The finish is the only part of a piece of furniture that every customer touches and every photograph shows. It is also the part most likely to differ between your first order and your third.
Colour matching is the most common quality complaint in imported case goods, and it is almost never caused by a factory trying to cheat. It is caused by a specification that described a colour in words.
Understanding the four finish systems tells you both why that happens and how to stop it.
The four systems
NC (nitrocellulose) is the traditional lacquer: fast-drying, easy to repair, thin-feeling, and the least durable against water and heat. Common on mid-price solid wood and Chinese-classical pieces.
PU (polyurethane) is the workhorse of Chinese furniture. It builds a thicker film, resists water and abrasion far better, and can be finished at any sheen. Most quality Foshan case goods are PU.
UV-cured finishes are sprayed or rolled and cured instantly under UV lamps. Extremely hard, extremely consistent, low emissions, and used on flat panels rather than shaped parts. If your item is panel-based, UV is a durability upgrade worth asking about.
Water-based finishes have the lowest emissions and are increasingly specified for markets with strict indoor-air requirements. They are less hard than PU unless properly formulated, and cost more.
Coats, and what a good finish actually is
Ask how many coats and what the schedule is. A proper PU finish on wood is roughly: sanding sealer, sand, primer, sand, colour or stain, one or two topcoats, with sanding between each. Cheap work is stain plus one topcoat.
The visible symptom of too few coats is that grain and pores show through as a rough texture rather than a smooth film, and edges look thin where the finish has pulled away. Run a fingernail across an edge and a corner — that is where a thin finish shows first and fails first.
Film thickness on quality furniture is measured in microns, and factories that care can tell you the number. Most cannot, which itself is informative.
Why colours drift between orders
Three reasons, in order of frequency. The reference was a word. "Walnut" is a family of colours, not a colour. The substrate changed. The same stain on a different batch of timber or a different veneer produces a different result, because stain is transparent. The lacquer supplier changed, and the new supplier's mix is a shade off.
The fix is physical. Keep a signed colour panel — a piece of the actual material with the actual finish, signed and dated by both parties, one copy kept by you and one by the factory. Reference it in every purchase order by its number.
Then specify tolerance: colour to match approved panel [number] under D65 daylight, ΔE ≤ 1.5. Factories capable of holding that will say so; those that are not will tell you by going quiet.
Showroom tests
The water test. Ask permission and put a drop of water on a horizontal surface for a minute. A good PU or UV finish leaves nothing; a thin NC finish leaves a mark.
The edge test. Look at the finish on an outside corner and the underside of a top. Cheap finishing stops where the eye stops.
The reflection test. Look along a large flat surface at a shallow angle towards a light. Orange peel, dust nibs and sanding scratches all appear immediately and are invisible face-on.
The smell test. A strong solvent smell in a finished piece that has been on display for weeks means it was rushed out of the finishing line, and it will off-gas in your customer's bedroom.
What to write down
Finish: [PU / UV / water-based], [sheen] gloss level measured at 60°, minimum [n] coats with sanding between, film thickness [x] microns, colour to match signed panel [number], ΔE ≤ 1.5. Finish applied to all surfaces including undersides and interior of case.
That last clause matters more than the rest. Unfinished undersides and interiors absorb humidity unevenly, which is what makes a panel bow, and bowed panels are the second most common warranty problem after colour.
